Trim installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What trim installation is

Trim installation cuts and fits casing around doors and windows, baseboard along floors, and other interior trim with mitered or coped corners. It is nailed to the studs, filled and caulked so the joints look seamless, and it finishes the edges where walls meet doors, windows and floors.

Signs you need it

  • Doors and windows have bare drywall edges, gaps or rough joints where the casing should be
  • Old trim is cracked, split or painted over so many times that the profiles have filled in
  • You are renovating a room and the new wall, door or window needs matching trim
  • The corners of the existing trim have gaps that open and close with the seasons
  • You want a more formal look, such as wider casing, a picture rail or a built-up profile

What the pro does

  • Measure each door, window and wall, and choose the profile, width and species for the casing and baseboard
  • Find the studs and mark them, then cut the miter or cope joints at the corners, testing each fit on the wall
  • Set the trim on the wall with a pin nailer or finish nails driven into the studs, keeping the reveal even
  • Set the nail heads below the surface, fill the holes with wood filler or a putty that matches the finish
  • Caulk the gaps between the trim and the wall, and between the trim and the floor, with a paintable caulk
  • Prime and paint or stain the trim, and check the joints in raking light to find any misses

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Linear footage of trim, the number of doors and windows, and the number of rooms
  • Profile complexity, such as a plain square casing versus a built-up or ornate profile
  • Wood species and whether the trim is painted poly, pine, oak or another species
  • Number of inside and outside corners that need miters or coping
  • Condition of the walls and whether the trim has to be removed and the wall repaired
  • Finish work, including priming, painting or staining, and the number of coats

What a written quote should spell out

  • Linear footage by room and by trim type, with doors and windows counted
  • Profile name and the width, and the wood species or material named
  • Corner method for each joint type, with miter or coping stated
  • Nailing, filling and caulk products named, with the paint or stain finish
  • Removal and disposal of old trim, if included, and the warranty on the install

Questions to ask before you hire

  • What profile and species do you recommend for my doors and baseboard, and why?
  • Do you cope or miter the inside corners, and how do you keep the joints tight?
  • How do you fasten the trim, and will you hit the studs?
  • Will the trim be filled and caulked, and what finish will it have at the joints?
  • What happens to the walls where the old trim came off?
  • Can you show me a room you trimmed with a similar profile and wall condition?

Red flags

  • The pro uses only glue and filler with no nails into the studs on the casing
  • The pro uses miters on every inside corner, which open up as the house moves
  • The pro does not fill or caulk the joints and says the trim will look finished
  • The pro paints the trim before the joints are filled, which shows the filler

What you can do yourself

Trim is a good project for a homeowner who measures carefully and has a miter saw and a pin nailer. Taking off old trim without damaging the wall, cutting coped joints, and matching a built-up profile take practice, so a first-time installer should start with a simple casing in a closet or a single room.

Licenses and permits

Trim installation commonly does not need a license or a permit, since it is finish work. Check with your state or local licensing agency only if the job changes framing or electrical in the room.

Trim installation questions

Should I use MDF or solid wood trim?

MDF takes paint smoothly and holds straight, while solid wood can be stained and handles wear better. Ask the pro which material suits the room and whether it will be painted or stained.

Why do the trim joints open up?

Usually the wood moves with humidity, or the joints were cut without a tight fit and then filled. Ask the pro how the joints are cut and how they will be caulked to hold up.

Can trim be installed on an uneven wall?

Yes, with scribing or shims at the wall, but a wall far out of plumb may need repair first. Ask the pro how they will fit the trim to the wall and what gaps will be caulked.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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